In this paper, a single probe (SP) has been designed for study plasma parameters of High enthalpy ICP-heated wind tunnel. It is found that the electron temperature in the core region is about 2.4 eV and that in the edge region is about 3–4 eV. At the maximum power of the High Enthalpy ICP-heated wind tunnel, the electron density reach 4.34 × 1013 cm-3. Meanwhile, the radial electron density distribution of SP is numerically integrated to calculate the line integral density, which is compared with the line integral density measured by 890 GHz HCN laser interferometer. The results show that the probe diagnosis results have the same trend as the laser diagnosis results. The line integral electron density measured by SP is 0.8 times higher than that measured by the HCN interferometer.